Disk producing apparatus

ABSTRACT

A photo film cassette includes a spool core ( 13 ) on which photo film is wound in a form of a roll. A cassette shell ( 3, 4 ) contains the spool core in rotatable fashion. In each of a pair of disks ( 16, 17 ), a bearing hole ( 16   a,    17   a ) is formed. The disks are secured to first and second ends of the spool core, and regulate edges of the photo film. To produce at least one kind of disk, a continuous sheet ( 27, 78, 88, 162, 171, 215 ) of thermoplastic synthetic resin is partially masked with a mask plate ( 48, 87, 160, 161, 170 ). A portion of the sheet emerging out of the mask plate is heated at temperature higher than a softening point of the sheet. The emerging portion is subjected to vacuum/air-pressure forming, so as to form a disk-like portion ( 20 ) in the sheet. The bearing hole and a contour of the disks is cut in the disk-like portion, to produce the disks.

This is a divisional of application Ser. No. 09/342,896 filed Jun. 29,1999 (now U.S. Pat. No. 6,136,261 issued Oct. 24, 2000), which is acontinuation of abandoned U.S. application Ser. No. 08/618,213 filedMar. 19, 1996, the disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk producing method and apparatusfor a photo film cassette. More particularly, the present inventionrelates to a method and apparatus for producing a plastic disk with highquality to be used in a photo film cassette.

2. Description Related to the Prior Art

U.S. Pat. No. 4,423,943 discloses a type of photo film cassette, ofwhich a leader of unexposed photo film is precontained in the cassetteshell, and advanced to an outside of the cassette shell when a spool isrotated in an unwinding direction. The spool is constituted by a spoolcore and two disks, which are disposed on the spool core, for contactwith the ends of a roll of the photo film, to render the turns of thephoto film neat. In the cassette of the leader-advancing type, it isnecessary to transmit rotation of the spool to the roll of the photofilm. To this end, the disks of the spool are provided with respectivering-like lips formed on their periphery and projected toward oneanother. The ring-like lips are located to cover edges of the outermostturn of the photo film, and prevent the roll from being loosened. Such acassette is suggested in U.S. Pat. Nos. 4,834,306, 4,848,693(corresponding to JP-A 2-18545), U.S. Pat. No. 5,031,852 (correspondingto JP-A 3-214153), U.S. Pat. No. 5,271,577 (corresponding to JP-A3-37645), and U.S. Pat. No. 5,407,146 (corresponding to JP-A 3-37645).

To advance the leader of the photo film, it is necessary to spread bothdisks in the vicinity of a photo film passageway, to release thering-like lips from regulation. The disks are rotatable, and are notrotated without being deformed. The disks are formed at the thickness of0.3 mm or less.

There is a suggestion of a disk producing method in U.S. Pat. No.5,211,348 (corresponding to JP-A 4-251841 and 5-119436). Continuousresin sheet of a thermoplastic type having small thickness is heated.The continuous sheet is deformed in accordance with the vacuum forming.The continuous sheet is moved into a punch/die set, where a punch deviceand a die device cut a circular contour and a bearing hole at eachdisk-like portion, to form the disks. However a shortcoming lies inthat, when one or both surfaces of thin resin continuous sheet areheated by a heater, the continuous sheet is likely to be softenedexcessively, melted and stuck on the heater, and cut down. JP-A 5-147606has a suggestion for overcoming the shortcoming, and discloses a use ofa mask plate having openings respectively greater than the contour ofeach disk to produce. The continuous sheet is masked by the mask plate.Portions emerging through the openings are heated. The portion excludedfrom the heating is cooled. The continuous sheet is subjected to thepress molding. It is thus possible to reduce the extent of melting ofthe continuous sheet in the heater.

The synthetic resin for disks must have strong characteristics withresistance to heat and flexural fatigue resistance, and are obliged tobe expensive. If the number of produced disks per unit amount of thecontinuous sheet is low, disks become costly. JP-A 6-67360 has asuggestion for solving this problem, and discloses that disks areproduced from continuous sheet with a great width in an arrangement of azigzag or a grid.

The disks must rotate without eccentricity in the cassette before thephoto film can be advanced properly. Concentricity of the disks betweenthe ring-like lips and the bearing holes should be acceptably high. Theconcentricity between the ring-like lip and the bearing hole depends oncoincidence between a position of the continuous sheet for the vacuumforming, and a stop position of the continuous sheet for the punching.Also, concentricity between the bearing hole and the disk contour shouldbe high. JP-A 61-51570 has a suggestion for obtaining highconcentricity, and discloses forming positioning holes in the continuoussheet. Positioning pins are inserted in the positioning holes, while thevacuum forming is effected and while the punching is effected.

To produce disks with precision, the continuous sheet subjected to thevacuum forming must be conveyed properly to a set position of a punchingmachine. For conveyance of continuous sheet or other similar material,conveying rollers, which are rotatable with the continuous sheet nipped,are widely used. Small changes in the set position are likely to occurdue to play of the rollers when the continuous sheet is stopped bystopping the rollers. JP-A 5-147606, in view of this, disclosesconveying holes formed near to edges of the continuous sheet. Conveyingpins are inserted in the conveying holes, and moved intermittently asfar as a predetermined amount, to convey the continuous sheet to the setposition regularly.

So far the vacuum forming in general has been used for producingarticles not requiring high precision in size, such as vessels foredibles. There have been no successful techniques known in the art, forproducing a disk with precision by the vacuum forming to be used in aphoto film cassette.

JP-A 5-147606 has a problem in that wrinkles are created in thecontinuous sheet in the course of the press molding, because a cooledportion of the continuous sheet is also pulled during the molding. JP-A6-67360 in turn has a problem in difficulties in heating and forming thewide continuous sheet with high regularity. Disks as produced haveconsiderably varied physical characteristics.

In JP-A 61-51570, the positioning holes operate to fix the continuoussheet completely. When distortion occurs in the continuous sheet due tounevenness in the vacuum forming to change the size of the continuoussheet, the continuous sheet as distorted is punched in the punchingstep. Irregularity in sizes occurs between disks as products. Thepositioning holes and the conveying holes may be formed at the time ofthe vacuum forming. It is however likely that a punch and a die forcutting those holes are swollen by heat remaining in the continuoussheet imported in the vacuum forming. Precision of the punch and the diesizes is therefore lowered.

SUMMARY OF THE INVENTION

In view of the foregoing problems, an object of the present invention isto provide a method and apparatus for producing a plastic disk from asheet without creating wrinkles in the sheet.

Another object of the present invention is to provide a method andapparatus for producing a plastic disk with high precision andregularity to be used in a photo film cassette.

In order to achieve the above and other objects and advantages of thisinvention, a sheet of thermoplastic synthetic resin is partially maskedwith a mask plate. A portion of the sheet emerging out of the mask plateis heated at temperature higher than a softening point of the sheet. Theemerging portion is subjected to vacuum forming, air-pressure forming,or vacuum/air-pressure forming in combination of vacuum forming andair-pressure forming, so as to form a disk-like portion in the sheet.The bearing hole and a contour of the disks is cut in the disk-likeportion, to produce the disks.

In a preferred embodiment, at least one opening is formed through themask device and having a size greater than the disks, the emergingportion emerging to be heated by the sheet heating unit while the sheetis accessed by the mask device.

The mask heating device heats a mask device at the temperature 10-50° C.lower than the softening point of the sheet.

In the present invention, the disk can be produced from a sheet withoutcreating wrinkles in the sheet.

In a variant of disk producing apparatus, the sheet has a predeterminedsize. A sheet supply unit, a sheet heating unit, a forming unit and apunching unit are arranged along one arc. An index table is disposed ata center of arrangement of the sheet supply unit, the sheet heatingunit, the forming unit and the punching unit, the sheet being mounted onthe index table, the index table being rotated intermittently, forpassing the sheet through the sheet supply unit, the sheet heating unit,the forming unit and the punching unit.

In another preferred embodiment, a retainable portion is formed in thesheet and near to an edge thereof when the disk-like portion is formed.The retainable portion of the sheet located in a conveying path isretained. The retainable portion while retained is moved in onedirection within a predetermined range, so as to convey the sheetintermittently.

A positioning portion associated respectively with the disk-like portionis formed when the disk-like portion is formed. The sheet is positionedwith the positioning portion, in cutting the bearing hole and thecontour of the disks.

Furthermore, at least one first bend slit is cut in an outside of thedisk-like portion to extend along part of a periphery thereof, the firstbend slit rendering a position of the disk-like portion adjustableminutely relative to the sheet.

The disk can be produced with high precision and regularity to be usedin a photo film cassette.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will becomemore apparent from the following detailed description when read inconnection with the accompanying drawings, in which:

FIG. 1 is an exploded perspective illustrating a photo film cassette;

FIGS. 2A and 2B are a perspective and a section both illustrating adisk;

FIG. 3 is a perspective illustrating a disk producing apparatus;

FIG. 4 is a section illustrating a vacuum/air-pressure forming unit;

FIG. 5 is a perspective illustrating a mask plate;

FIG. 6 is a section illustrating the forming unit while the sheet issqueezed;

FIG. 7 is a section illustrating the forming unit while the sheet isheated;

FIG. 8 is a section illustrating the forming unit during suction andpressurization;

FIG. 9 is a perspective illustrating another preferred mask plate;

FIG. 10 is a perspective illustrating still another preferred maskplate;

FIG. 11 is an explanatory view illustrating a variant of apparatus inwhich disks are produced in arrangement of a matrix;

FIG. 12 is an explanatory view illustrating another preferred diskproducing apparatus;

FIG. 13 is a section illustrating one of sheet holders as closed;

FIG. 14 is a section illustrating the one sheet holder while a sheet issupplied;

FIG. 15 is a section illustrating the one sheet holder while a sheet isheated;

FIG. 16 is a section illustrating the one sheet holder during suctionand pressurization;

FIG. 17 is a plan illustrating another preferred sheet holder;

FIG. 18 is a section illustrating still another preferred sheet holder;

FIG. 19 is a chart illustrating a flow of a further preferred diskproducing apparatus;

FIG. 20 is a perspective illustrating a mask device;

FIG. 21 is a section illustrating a sheet heating unit;

FIGS. 22A and 22B are explanatory views illustrating a sheet aftervacuum/air-pressure forming;

FIG. 22C is a section illustrating a forming unit;

FIG. 23 is an explanatory view illustrating a sheet conveyor;

FIGS. 24A and 24B are explanatory views illustrating the sheet after theslit punching;

FIGS. 25A and 25B are sections illustrating operation of a firstpunching unit;

FIGS. 26A and 26B are sections illustrating operation of a secondpunching unit;

FIG. 27 is an explanatory view illustrating a sheet in which two linesof disk-like portions are formed;

FIG. 28 is an explanatory view illustrating the sheet after the slitpunching;

FIG. 29 is an explanatory view illustrating a sheet in which two kindsof disks are being produced; and

FIG. 30 is a plan illustrating a variant of sheet heater.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENTINVENTION

In FIG. 1, a photo film cassette 2 includes upper and lower shell halves3 and 4, a spool 5, a port shutter member 6, a lock 7, and a sticker orlabel 8. The shell halves 3 and 4 are respectively formed from plastics.The spool 5 is contained between the shell halves 3 and 4. The sticker 8is attached to the outside of the shell halves 3 and 4.

A photo film port 10 is formed between the shell halves 3 and 4 forpassage of photo film 9. The port shutter 6 for opening/closing thephoto film port 10 is contained in a middle position of the photo filmport 10. A separating claw 11 is formed on the lower shell half 4 in aninnermost position of the photo film port 10, for separation of a leaderof the photo film 9 around the spool 5 from the roll, to direct it tothe photo film port 10.

The spool 5 includes a spool core 13, a data plate 14, a barrel member15, and disks 16 and 17. A trailer of the photo film 9 is secured to thespool core 13 and wound thereabout. The data plate 14 is formed with adistal end of the spool core 13. The barrel member 15 is secured toanother distal end of the spool core 13. The disks 16 and 17 are securedto the spool core 13 between the data plate 14 and the barrel member 15.There is a bar code sticker 18 on which a bar code is printed forrepresenting various data related to the photo film 9, and which isattached to the data plate 14. The bar code is read by a camera or otherdevices.

The barrel member 15 includes an indicator plate 15 a for indicating astatus of exposing the photo film 9 in externally visible fashion to auser, and a gear 15 b for locking the spool 5. The indicator plate 15 ais positioned inside any of a plurality of indicating windows formed inan end face of the shell halves 3 and 4, and shows one of unexposed,partially exposed, all exposed and developed statuses as informationassociated with each of the windows. When the port shutter 6 has aclosed position, the gear 15 b is engaged with the lock 7, whichdisables the spool 5 from rotating. When the port shutter 6 has an openposition, the lock 7 is moved away from the gear 15 b to enable thespool 5 to rotate.

The disks 16 and 17 are shaped like a two-stepped dish and haverespective bearing holes 16 a and 17 a through which the spool core 13is inserted. Around the disks 16 and 17 are formed ring-like lips 16 band 17 b, which cover ends of a roll of the photo film 9 about the spoolcore 13, to keep the roll from being loosened in the photo film cassette2. The disks 16 and 17 are formed of flexible plastics for easydeformation during advancement of the photo film 9, and have thicknessof 0.3 mm or less.

In FIGS. 2A and 2B, four slots 23 in an arc shape are formed around thebearing hole 17 a in the disk 17. An inner face of the barrel member 15is provided with ratchet claws 24, which are inserted in two of theslots 23. When the spool 5 is rotated in an unwinding direction, theratchet claws 24 are engaged with the slots 23, to rotate the disk 17with the spool core 13. When the spool 5 is rotated in a windingdirection in reverse, the ratchet claws 24 rotate past the slots 23, notto transmit rotation of the spool core 13 to the disk 17.

Transmission of rotation to the disk 17 is changed over according to adirection of rotating the spool 5. Friction is reduced by coincidence inrotation between the photo film 9 and the disk 17 about the spool 5 inadvancement of the photo film 9. Only small force applied to the spool 5for rotation is required for advancement of the photo film 9. As thedisk 17 is rotated individually in rewinding of the photo film, thephoto film 9 is wound toward the inside of the ring-like lip 17 bwithout hindrance.

Before and after use of the photo film cassette 2, the leader of thephoto film 9 is entirely wound in the photo film cassette 2. The portshutter 6 has the closed position to close the photo film port 10. Noambient light comes into the photo film cassette 2 through the photofilm port 10. The spool 5 is locked by the lock 7 and kept fromaccidentally rotating. When the port shutter 6 opens the separating claw11 and the spool 5 is rotated in the clockwise direction, the leader ofthe photo film 9 is separated by the separating claw 11 to exit throughthe photo film port 10.

A disk producing apparatus 26 of the present invention is describednext. As illustrated in FIG. 3, the disk producing apparatus 26 isadapted to produce the disks 17. The disk producing apparatus 26includes a sheet supply unit 28, a forming unit 29, a first punchingunit 30, a second punching unit 31, a disk withdrawing unit 32 and asheet winding unit 33, all of which are arranged on a stand 34. Thesheet supply unit 28 supplies continuous sheet 27 of thermoplastic resinas material for the disks 17. The forming unit 29 applies heat to thecontinuous sheet 27 from the sheet supply unit 28, subjects thecontinuous sheet 27 to the vacuum/air-pressure forming, and forms pluraldisk-like portions, for example five (5) disk-like portions on thecontinuous sheet 27. The first punching unit 30 cuts the bearing hole 17a and the slots 23 in the disk-like portions. The second punching unit31 cuts the contour of the disks 17 at the disk-like portions. The diskwithdrawing unit 32 withdraws the continuous sheet 27 from the diskproducing apparatus 26. The sheet winding unit 33 draws the continuoussheet 27 from the sheet supply unit 28, while winding the continuoussheet 27 subsequent to the punching of the disks 17.

The continuous sheet 27 is 0.15 mm thick, and formed of resin ofpolystyrene-modified polyphenylene ether with elastomer added thereto.The ratio of polystyrene and polyphenylene ether is 3:7. The proportionof elastomer is 12 wt. %.

The sheet supply unit 28 is constituted by a drum 36 and a brake device37. The continuous sheet 27 is wound on the drum 36. The brake device 37applies load to the drum 36 to apply tension to the continuous sheet 27while drawn by the sheet winding unit 33. The sheet winding unit 33 isconstituted by a drum 38 and a motor 39. The drum 38 is adapted towinding the continuous sheet 27 as punched. The motor 39 rotates thedrum 38. To guide the continuous sheet 27, guide rollers 40 are disposedin the disk producing apparatus 26 between the sheet supply unit 28, theforming unit 29, the first punching unit 30, the second punching unit31, the disk withdrawing unit 32 and the sheet winding unit 33.

In the forming unit 29, a stationary support 43 is disposed on the stand34 as illustrated in FIG. 4. A movable support 45 is arranged over thestationary support 43, and movable vertically along guide shafts 44. Afemale mold plate 46 is mounted on the stationary support 43, andincludes five (5) female molds 46 a aligned in the conveying directionof the continuous sheet 27. A male mold plate 47 is mounted on themovable support 45, and includes five (5) male molds 47 a.

There is a mask plate 48 disposed between the supports 43 and 45 forholding the continuous sheet 27 between it and the female mold plate 46.The forming unit 29 also has an apparatus for heating the sheet. A sheetheater 49 is disposed beside the forming unit 29, to be inserted betweenthe supports 43 and 45. To move the movable support 45 up and down,hydraulic cylinders, cams, and the like are used.

There is an air mouthpiece 51 formed in the female mold plate 46 to comethrough each of the female molds 46 a. The air mouthpiece 51 isconnected to an air passageway 52 which is formed through the stationarysupport 43 and comes to be open in a lateral face of the stationarysupport 43. A pipe 53 is secured to the stationary support 43 to connectthe air passageway 52 to a vacuum pump for air suction. There is an airmouthpiece 55 formed in the male mold plate 47 to come through each ofthe male molds 47 a. The air mouthpiece 55 is connected to an airpassageway 56 which is formed through the movable support 45 and comesto be open in a lateral face of the movable support 45. A pipe 57 issecured to the movable support 45 to connect the air passageway 56 to acompressor for air pressurization. The air suction and the airpressurization keep the continuous sheet 27 into tight contact with thefemale molds 46 a, to form disk-like portions.

The mask plate 48 is rectangular as illustrated in FIG. 5, and has five(5) openings 59 formed through it and arranged at a regular interval inits longitudinal direction. The openings 59 have a diameter greater thana diameter of the disks 17. As illustrated in FIG. 4, the mask plate 48is movable up and down in the vertical direction along guide shafts 60,which are disposed in positions inside positions of the guide shafts 44for the movable support 45. There is a spring 61 having greater biasingforce, arranged between the movable support 45 and the mask plate 48 andaround each of the guide shafts 60. There is a spring 62 having smallerbiasing force than the spring 61, arranged between the stationarysupport 43 and the mask plate 48 and around each of the guide shafts 60.With the springs 61 and 62 balanced, the mask plate 48 when not in usehas a position nearer to the stationary support 43 and shiftable betweenthe supports 43 and 45.

The continuous sheet 27 is conveyed between the female mold plate 46 andthe mask plate 48 lying over the same. Once the continuous sheet 27stops being conveyed, the movable support 45 is lowered by the hydrauliccylinders, the cams, and the like at a small amount as illustrated inFIG. 6. The spring 61 over the mask plate 48 is pressed, to bias themask plate 48 downwards along the guide shafts 60. The spring 62 underthe mask plate 48 is weaker than the spring 61, and are compressed bythe mask plate 48, to squeeze the continuous sheet 27 between the maskplate 48 and the female mold plate 46.

When the continuous sheet 27 is inserted between the female mold plate46 and the mask plate 48, the sheet heater 49 standing by beside theforming unit 29 is driven by an air cylinder or solenoid, and insertedbetween the movable support 45 and the mask plate 48 as illustrated inFIG. 7. The sheet heater 49 includes a block 49 a and a cartridge heater49 b. The block 49 a is formed of material with high heat conductivity,such as iron or aluminum. The cartridge heater 49 b is incorporated inthe block 49 a. The sheet heater 49 is controlled so that a surface ofthe block 49 a has temperature of 400±5° C. Heat of the sheet heater 49operates to portions of the continuous sheet 27 emerging through theopenings 59 in the mask plate 48, to render the portions as hot as 150°C.

When the continuous sheet 27 is heated to a predetermined temperature,the sheet heater 49 is moved aside and out of the forming unit 29 by theair cylinder or solenoid. Only the portions of the continuous sheet 27required in the vacuum/air-pressure forming are heated, so that thecontinuous sheet 27 is not melted or stuck on the mold set inirrecoverable fashion. The continuous sheet 27 finishes being heatedwhen its temperature as measured comes up to a predetermined value. Itis also possible to measure preheating time experimentally for heatingthe continuous sheet 27 with the sheet heater 49, and to retract thesheet heater 49 upon the lapse of the measured time.

As illustrated in FIG. 5, an inside of the mask plate 48 has a liquidpassageway 64, through which hot liquid medium, such as water orspecialty oil for applying heat, is circulated inside the mask plate 48.The liquid passageway 64 is disposed around the openings 59. The hotliquid medium is entered into one end of the liquid passageway 64, flowsthrough the liquid passageway 64 to heat the mask plate 48 to thetemperature 10-50° C. lower than a softening point of the continuoussheet 27, and exited from another end of the liquid passageway 64 to theoutside. Thus the portion of the continuous sheet 27 masked by the maskplate 48 is heated to the temperature lower than its softening point,and can be swelled at a smaller amount at the time of the forming. It isthus possible to avoid occurrence of wrinkles on the continuous sheet27.

As is not shown, distal ends of the liquid passageway 64 are connectedto respective pipes having flexibility and resistance to heat. Distalends of the pipes opposite to the liquid passageway 64 are connected toa liquid pump which is disposed in the stand 34 for the hot liquidmedium. The inside of the stand 34 contains a liquid tank and a heaterfor heating the liquid medium, as well as the liquid pump.

At the end of heating the continuous sheet 27, the sheet heater 49 ismoved out of the space between the movable support 45 and the mask plate48. The movable support 45 is lowered further by hydraulic cylinders,cams, and the like. With the movable support 45 lowered, the male molds47 a are inserted into the openings 59 formed in the mask plate 48 asillustrated in FIG. 8, and then into the female molds 46 a.

In lowering the movable support 45, the air pressurization is effectedthrough the air mouthpiece 55 in the male molds 47 a, to press thecontinuous sheet 27 against the female molds 46 a. The air suction iseffected through the air mouthpiece 51 in the female molds 46 a, to keepthe continuous sheet 27 in tight contact with the female molds 46 a, toform five (5) disk-like portions 20 in the continuous sheet 27. Thus thevacuum/air-pressure forming in combination of the air pressurization andthe air suction makes it possible to form the disk-like portions 20 withhigh precision, as the continuous sheet 27 is contacted on the mold setin tighter fashion than the uncombined use of either of the airpressurization and the air suction. The number of the five disk-likeportions 20 is appropriate, because it is possible to have only smallunevenness in heating and forming of the disk-like portions 20.

The first punching unit 30 is described in detail next. As illustratedin FIG. 3, the first punching unit 30 includes a stationary support 30 aand a movable support 30 b. The stationary support 30 a has a diesecured thereto for forming the bearing hole 17 a and the slots 23 inthe disk-like portions 20. The movable support 30 b has a punch securedthereto and movable vertically up and down along guide shafts 30 c. Themovable support 30 b is driven by the hydraulic cylinders, cams, and thelike. Scraps created by forming the bearing hole 17 a and the slots 23in the first punching unit 30 are dropped through the die, passedthrough a path 66 under the stationary support 30 a, and exited throughan exit 67 formed in a side of the stand 34.

The second punching unit 31 is constructed substantially the same as thefirst punching unit 30, and includes a stationary support 31 a and amovable support 31 b. The stationary support 31 a has a die securedthereto for forming the contour of the disk-like portions 20. Themovable support 31 b has a punch secured thereto and movable verticallyup and down along guide shafts 31 c. The second punching unit 31 is alsoprovided with a push back device known in the art, so that the disks 17after being punched away can be returned into punch holes in thecontinuous sheet 27 after the punching. The disks 17 as punched arereturned to the continuous sheet 27, of which conveyance causes thedisks 17 to move to the disk withdrawing unit 32.

The disk withdrawing unit 32 includes a support plate 69, a disk lift 70and an arm 72. On the support plate 69 is placed the continuous sheet 27in which the disks 17 is still kept together. The disk lift 70 removesthe disks 17 from the continuous sheet 27 while lifting it. The arm 72swings the disk lift 70 and moves it to a disk container 71. For thekeeping of the disks 17 in the disk lift 70, air suction, electrostaticsuction, or a mechanical grasping structure may be utilized. It isnecessary that the disk lift 70 is released from the disk keeping uponmovement to the disk container 71. It is also possible to eliminate thedisk with-drawing unit 32, and to exit the disks 17 through an exitformed in the stand 34 in a similar form to the exit 67 at the firstpunching unit 30.

Operation of the above construction is described. As illustrated in FIG.3, a starting command is entered into the disk producing apparatus 26,in which the continuous sheet 27 wound on the drum 36 in the sheetsupply unit 28 is drawn by rotation of the sheet winding unit 33, andguided by the guide rollers 40. As illustrated in FIG. 4, the continuoussheet 27 is conveyed between the female mold plate 46 and the mask plate48 in the forming unit 29. At the same time, the cartridge heater 49 bin the sheet heater 49 is energized. The liquid medium, such as water orspecialty oil for applying heat, starts being heated and flowing intothe mask plate 48. The predetermined temperature is obtained byprestarting heating the sheet heater 49 and the mask plate 48, so thatthe time for heating the continuous sheet 27 can be short to raiseefficiency in producing the disks 17.

Once the continuous sheet 27 is stopped, the movable support 45, asillustrated in FIG. 6, is lowered at a smaller amount by the hydrauliccylinders, cams, and the like. Then the spring 61 biases the mask plate48, which compresses the spring 62 to squeeze the continuous sheet 27between it and the female mold plate 46.

While the continuous sheet 27 is entirely squeezed on the mask plate 48,the sheet heater 49 is inserted between the movable support 45 and themask plate 48 by the air cylinder or solenoid, as illustrated in FIG. 7.The block 49 a of the sheet heater 49 has been heated to the temperatureof 400±5° C. At the same time as the insertion into the forming unit 29,the sheet heater 49 starts heating the continuous sheet 27. The sheetheater 49 heats only the portions of the continuous sheet 27 emergingthrough the openings 59 in the mask plate 48, to render the portions ashot as 150° C.

Only the portions of the continuous sheet 27 required in thevacuum/air-pressure forming are heated, so that the continuous sheet 27is not melted or stuck on the mold set in irrecoverable fashion. The hotliquid medium such as water or specialty oil is circulated through theliquid passageway 64. The portion of the continuous sheet 27 masked incontact with the mask plate 48 is heated to the temperature lower thanits softening point by 10-50° C.

When the continuous sheet 27 is at the predetermined temperature, thesheet heater 49 is moved away from between the movable support 45 andthe mask plate 48 by the air cylinder or solenoid. As illustrated inFIG. 8, the movable support 45 is further lowered by the hydrauliccylinders, cams, and the like. The male molds 47 a are respectivelyinserted through the openings 59 of the mask plate 48, and into thefemale molds 46 a.

At the same time as the descent of the movable support 45, a vacuum pumpconnected to the air passageway 52 of the stationary support 43 startsthe air suction. A compressor connected to the air passageway 56 of themovable support 45 starts the air pressurization. Then the male molds 47a press the continuous sheet 27 against the female molds 46 a, throughwhich the continuous sheet 27 is sucked. The disk-like portions 20 areformed in the continuous sheet 27 with high precision. The continuoussheet 27 is not deformed in un-wanted fashion, as retained between themask plate 4B and the female mold plate 46. The portion other than theportions with the disk-like portions 20 is also heated by the mask plate48 and swellable sufficiently, so that no wrinkles or breakage occurs.

The movable support 45, while lowered, is left to stand for apredetermined duration to cool the continuous sheet 27, and then raisedagain by the hydraulic cylinders, cams, and the like. The mask plate 48is released from the bias of the spring 61, and has a position betweenthe supports 43 and 45 with the springs 61 and 62 balanced asillustrated in FIG. 4. The continuous sheet 27 restarts being conveyed.A section of the continuous sheet 27 having been provided with thedisk-like portions 20 is conveyed to the first punching unit 30.

In the first punching unit 30, the movable support 30 b is lowered bythe hydraulic cylinders, cams, and the like, to cause a set of a punchand a die to cut the bearing hole 17 a and four of the slots 23 in thedisk-like portions 20. The scraps created by the cutting are passedthrough the die and the path 66, and exited from the exit 67 in thestand 34. At the time of the cutting, five other disk-like portions 20are formed by the forming unit 29 on the continuous sheet 27.

In the second punching unit 31, the movable support 31 b is lowered tocut the contour of the disk-like portions 20 from the continuous sheet27 by means of the punch and the die. The disks 17 cut from thecontinuous sheet 27 are turned to the continuous sheet 27 by the pushback device. After the punching in the second punching unit 31, themovable support 31 b is raised. The continuous sheet 27 is conveyedagain. In the conveyance, the disks 17 are conveyed with the continuoussheet 27 and transferred to the disk withdrawing unit 32.

In the disk withdrawing unit 32, the disk lift 70 removes the disks 17from the continuous sheet 27 by sucking or grasping the disks 17. Whilethe disk lift 70 retains the disks 17, the arm 72 rotates to move thedisk lift 70 to a position above the disk container 71. Then the disklift 70 is released from the suction or grasping, to let the disks 17drop into the disk container 71 which receives the disks 17. The diskcontainer 71, when filled with a great number of the disks 17, isconveyed to a line of assembling the spool 5. In place of the diskcontainer 71 as filled, a new container is positioned in the diskwithdrawing unit 32. In repetition of those steps, the disks 17 areproduced in successive fashion.

In the above embodiment, the hot liquid medium such as water orspecialty oil is used to heat the mask plate 48. It is possible to useelectrically heated wires or a feeder slip ring. It is possible that thesheet heater 49 is additionally operated to preheat the mask plate 48.Note that, if there is an undercut on a product to be formed by thevacuum/air-pressure forming, it is preferable to provide the female moldplate 46 with a push-out mechanism for pushing the continuous sheet 27up.

The number of the openings 59 in the mask plate 48 for defining theheated range of the continuous sheet 27 is equal to the number of thedisk-like portions 20. However, the number of openings 75 in the maskplate 48 can be half of the number of the disk-like portions 20, asillustrated in FIG. 9. In other words, each of the openings 75 can betwice as large as one of the disk-like portions 20. Further, a singleopening 76 can be formed for a train of the plurality of the disk-likeportions 20 to be formed at one time, as illustrated in FIG. 10. In theabove embodiment, the five of the disk-like portions 20 are formed atone time. It is possible at one time to form four or less, or six ormore of the disk-like portions 20.

In the above embodiment, the continuous sheet 27 has a width associatedwith forming of only one of the disk-like portions 20. A plurality ofthe disk-like portions 20 are either formed and punched at one time inthe longitudinal direction of the continuous sheet 27. However a widecontinuous sheet 78 can be used as illustrated in FIG. 11. To form andpunch a plurality of the disk-like portions 20 in a matrix form at onetime, there are arranged a vacuum/air-pressure forming unit 79, a firstpunching unit 80, a second punching unit 81, and a disk withdrawing unit82.

Another preferred apparatus 85 for producing a disk is described next.FIG. 12 schematically illustrates the disk producing apparatus 85inclusive of an index table 86. The index table 86 is rotatable inintermittent fashion in the counterclockwise direction. Eight (8) sheetholders 87 are secured to the index table 86 as a mask device. Aroundthe index table 86 are arranged units of respective steps for producingthe disks 17, in stations where each of the sheet holders 87 is stoppedin the intermittent rotation of the index table 86.

Those units are a sheet supply unit 89, a sheet heating unit 90, avacuum/air-pressure forming unit 91, a sheet cooling unit 92, a firstpunching unit 93, a second punching unit 94, a third punching unit 95,and a sheet exit unit 96, arranged in the order listed. The sheet supplyunit 89 cuts a single sheet 88 of a predetermined size from thecontinuous sheet 27 wound as a roll, and supplies a closely positionedone of the sheet holders 87 with the sheet 88. The sheet heating unit 90heats the sheet 88 supported in the one sheet holder 87. The formingunit 91 subjects the sheet 88 to the vacuum/air-pressure forming, andforms five of the disk-like portions 20. The sheet cooling unit 92 coolsthe sheet 88. The first punching unit 93 cuts the bearing hole 17 a inthe disk-like portions 20. The second punching unit 94 cuts the slots 23in the disk-like portions 20. The third punching unit 95 cuts thecontour of the disk-like portions 20 from the sheet 88 to form the disks17. The sheet exit unit 96 removes the sheet 88 from the sheet holder 87after cutting away the disks 17.

The one sheet holder 87, as illustrated in FIG. 13, is constituted by anupper mask plate 98 and a lower mask plate 99. The lower mask plate 99has a receiving recess 100 and five (5) openings 101. The receivingrecess 100 receives the sheet 88. The openings 101 come through thebottom of the receiving recess 100, and respectively have a greaterdiameter than a diameter of the disks 17. The upper mask plate 98 has apressing ridge 102 and five (5) openings 103. The pressing ridge 102 isfitted in the receiving recess 100 to squeeze the sheet 88. The openings103 come through the pressing ridge 102, and respectively have a greaterdiameter than a diameter of the disks 17.

There are four guide shafts 106 mounted through the index table 86 andslidable vertically via slide bearings 105. The mask plates 98 and 99receives insertion of the guide shafts 106 and slidable vertically viaslide bearings 107 and 108.

Upper and lower ends 106 a and 106 b of the guide shafts 106 arerespectively fixed on retaining plates 110 and 111, to keep adjacentones of the guide shafts 106 positioned at a regular interval. Two ringsor flanges 112 and 113 are disposed on each of the guide shafts 106, andrespectively below and above the index table 86. The flange 112 definesan upper limit of sliding the guide shafts 106. The flange 113 defines alower limit of sliding the guide shafts 106.

The lower mask plate 99 is disposed between the flange 113 and the indextable 86. The upper mask plate 98 is disposed between the flange 113 andthe retaining plate 110. There are recesses 115 formed in the lower maskplate 99 and located over the slide bearings 108, for receiving theflange 113. A sufficient space can be made between the mask plates 98and 99 for insertion of the sheet 88, by the virtue of the recesses 115.

There is a spring 116 having greater biasing force, arranged between thelower mask plate 99 and the index table 86 and around each of the guideshafts 106. There is a spring 117 having smaller biasing force than thespring 116, arranged between the retaining plate 110 and the upper maskplate 98 and around each of the guide shafts 106. When not in use, thespring 116 raises the lower mask plate 99 so as to contact the flange113 on the lower mask plate 99 and contact the flange 112 on the indextable 86. At the same time, the spring 117 causes the upper mask plate98 to contact on the lower mask plate 99.

There is a shaft 119 which is disposed to extend from the retainingplate 111, and comes downwards therefrom. A connector plate 120 issecured to a bottom end of the shaft 119. When the shaft 119 is pulleddownwards via the connector plate 120, the guide shafts 106 are alsopulled down. The flange 113 of the guide shafts 106 lower the lower maskplate 99 against the bias of the spring 116.

There is a shaft 121 which is disposed to extend from the upper maskplate 98, and comes upwards and through the retaining plate 110. Aconnector plate 122 is secured to a top end of the shaft 121. When theshaft 121 is pulled upwards via the connector plate 122, the upper maskplate 98 is raised against the bias of the spring 117. With theconnector plates 120 and 122 pulled away from one another, there takesplace a space between the mask plates 98 and 99 to smooth the supply andexit of the sheet 88.

The sheet supply unit 89 has a pair of solenoids 124 and 125respectively arranged on the top and the bottom in stationary fashion.The solenoids 124 and 125 have plungers 126 and 127, which are protrudedwhen not energized, and retracted therein when energized. Tips of theplungers 126 and 127 have respective two-bracketed connectors 128 and129 for engagement. When the one sheet holder 87 is rotated to the sheetsupply unit 89, the two-bracketed connectors 128 and 129 receiveinsertion of the connector plate 120 of the retaining plate 111 and theconnector plate 122 of the upper mask plate 98.

When the solenoid 125 is energized, the plunger 127 is pulled to theinside of the solenoid 125. The two-bracketed connector 129 is engagedwith the connector plate 120 to pull the guide shafts 106 downwards. Theflange 113 pulls the lower mask plate 99 down against the bias of thespring 116. A downstroke of the lower mask plate 99 is adjustableaccording to an extent of a projecting amount of an adjusting screw 131on a bottom of the lower mask plate 99. In a similar manner, when thesolenoid 124 is energized, the upper mask plate 98 is pulled up by theplunger 126 against the bias of the spring 117. Then the space betweenthe mask plates 98 and 99 is widely formed as illustrated in FIG. 14.

A retaining arm 133 retains the sheet 88 in the air suction. When theone sheet holder 87 is open, the retaining arm 133 with the sheet 88 isdriven by an air cylinder or solenoid, and inserted between the maskplates 98 and 99 of the sheet supply unit 89. Then the air suction ofthe retaining arm 133 is stopped. The sheet 88 is dropped into thereceiving recess 100 of the lower mask plate 99.

A suction device 135, for example a vacuum pump device, is disposedunder the lower mask plate 99, for sucking the sheet 88 through theopenings 101. The suction device 135 has a nozzle 136, which is insertedin the openings 101 when the lower mask plate 99 is pulled down. Even ifthe sheet 88 has a considerable curl, the sheet 88 can be reliablypositioned in the receiving recess 100. While the suction device 135 iseffecting the air suction, the solenoids 124 and 125 stop beingenergized. Then the mask plates 98 and 99 are pressed by the spring 117and the spring 116. The sheet 88 is squeezed between the mask plates 98and 99. With the one sheet holder 87 closed, there takes place a spacebetween the one sheet holder 87 and the suction device 135 asillustrated in FIG. 13. The index table 86 becomes rotatable againwithout a problem.

As illustrated in FIG. 15, the sheet heating unit 90 has a solenoid 138only on the bottom. The solenoid 138 operates to lower the one sheetholder 87, not to open the one sheet holder 87. When the solenoid 138 isenergized and the connector plate 120 is pulled, the lower mask plate 99is lowered against the spring 116. The one sheet holder 87 is loweredwhile the sheet 88 is kept retained in the one sheet holder 87, as theupper mask plate 98 is biased downwards by the spring 117.

In the sheet heating unit 90, a lower sheet heater 140 is disposed underthe lower mask plate 99. The lower sheet heater 140 includes a heaterhead 141 and a cartridge heater. The heater head 141 is formed ofmaterial with high heat conductivity, such as iron or aluminum. Thecartridge heater is incorporated in the heater head 141. When the onesheet holder 87 is pulled down, the heater head 141 of the lower sheetheater 140 is inserted into the openings 101. There is an upper sheetheater 142 disposed above the upper mask plate 98. The upper sheetheater 142 is moved down by an air cylinder, a solenoid and the like notshown, to insert a heater head 143 into the openings 103. In the sheetheating unit 90, portions of the sheet 88 externally emerging throughthe openings 101 and 103 are heated as hot as 150° C. Only the portionsof the sheet 88 to be formed in the vacuum/air-pressure forming areheated, so that the sheet 88 is not melted or stuck on the one sheetholder 87 in irrecoverable fashion.

The temperature is measured near to the sheet 88. When the heating ofthe sheet 88 is finished, the upper sheet heater 142 is raised. Thesolenoid 138 finishes being energized. The one sheet holder 87 is movedupwards by the spring 116.

An inside of the upper mask plate 98 has a liquid passageway 145,through which hot liquid medium, such as water or specialty oil forapplying heat, is circulated inside the upper mask plate 98. The liquidpassageway 145 is disposed around the openings 103. The hot liquidmedium is entered into an entrance pipe 146 of the liquid passageway145, flows through the liquid passageway 145 to heat the one sheetholder 87 to the temperature 10-50° C. lower than a softening point ofthe sheet 88, and exited from an exit pipe 147 of the liquid passageway145 to the outside.

The pipes 146 and 147 are passed through a rotary joint 148 (See FIG.12) disposed at the center of the index table 86, and connected to aliquid pump which is disposed under the index table 86 for the hotliquid medium. Under the index table 86 are arranged a liquid tank and aheater for heating the liquid medium, as well as the liquid pump. Notethat a passageway 149, and pipes 150 and 151 associated with the lowermask plate 99 are similar to those elements, and are not describedfurther.

In the forming unit 91, the one sheet holder 87 is pulled down in amanner similar to the sheet heating unit 90. As illustrated in FIG. 16,a female mold 153 is disposed under the lower mask plate 99. With theone sheet holder 87 pulled down, the female mold 153 is inserted in theopenings 101. There is a male mold 154 disposed above the upper maskplate 98. The male mold 154 is moved down by an air cylinder, a solenoidand the like not shown, and inserted into the openings 103. A suckingpassageway 155 is formed to communicate through the female mold 153 forthe air suction. A sucking passageway 156 is formed to communicatethrough the male mold 154 for the air pressurization. At the same timeas the descent of the one sheet holder 87 and before the descent of themale mold 154, the air suction starts being effected through the suckingpassageway 155. The air pressurization starts being effected through thesucking passageway 156. The sheet 88 is tightly contacted on the femalemold 153. The five (5) of the disk-like portions 20 are formed in thesheet 88 with high precision.

Thus the portion of the sheet 88 masked in the one sheet holder 87 isheated to the temperature 10-50° C. lower than its softening point, toavoid occurrence of wrinkles on the sheet 88. The sheet 88 is notdeformed in unwanted fashion, as retained in the one sheet holder 87.

After the vacuum/air-pressure forming, the sheet cooling unit 92 isadapted to cooling the sheet 88 and in advance of next unit for thepunching. Note that it is possible to cool the sheet 88 in the formingunit 91, and to install a unit for withdrawing disks in place of thesheet cooling unit 92.

The first punching unit 93 is adapted to cutting the bearing hole 17 ain the disk-like portions 20 formed on the sheet 88. A punch and a dieare operated via the openings 101 and 103 respectively in the maskplates 98 and 99. Scraps created by cutting the bearing hole 17 a aredropped through the die to exit to the outside, in a manner similar tothe former embodiment of FIGS. 1-11.

The second punching unit 94 is adapted to cutting the slots 23 of an arcshape in the disk-like portions 20 formed on the sheet 88. In fashionsimilar to the first punching unit 93, a punch and a die are operatedvia the openings 101 and 103 respectively in the mask plates 98 and 99.Scraps created by cutting the slots 23 are dropped through the die toexit to the outside.

The third punching unit 95 is adapted to cutting the contour of thedisk-like portions 20 from the sheet 88. In fashion similar to thepunching units 93 and 94, a punch and a die are operated. The disks 17as cut out are dropped through the die, and contained in a diskcontainer disposed under the die. This being so, the precision of thedisks 17 as produced is heightened by precise positioning of the sheetholders 87 in the successive units, so that eccentricity between theforming and the punching is reduced.

It is also possible to provide the third punching unit 95 with a pushback device, so that the disks 17 after being punched away can bereturned to the sheet 88 after the punching. For this structure, a diskwithdrawing unit may be provided for withdrawing the disks 17 from thesheet 88. Also, it is alternatively possible that the bearing hole 17 a,the slots 23 and the contour is cut by the first punching unit 93, andthe punching units 94 and 95 are eliminated.

The sheet exit unit 96 is structurally similar to the sheet supply unit89, and has two solenoids respectively arranged on the top and thebottom in stationary fashion, for opening a space between the maskplates 98 and 99. There is a retaining arm similar to the retaining arm133 of the sheet supply unit 89. When the one sheet holder 87 is open,the retaining arm is driven by an air cylinder or solenoid, and insertedinto the one sheet holder 87. The retaining arm takes up the sheet 88from the receiving recess 100, retains it by the air suction, is movedout of the one sheet holder 87, and exit the sheet 88 from the one sheetholder 87 after punching of the disks 17. Note that the sheet exit unit96 can have an air cylinder or hydraulic cylinder instead of thesolenoid, for driving the one sheet holder 87.

Operation of the above embodiment is described now. In FIG. 12, astarting command is entered into the disk producing apparatus 85, whichstarts intermittent rotation of the index table 86. At the same time asthis, the upper sheet heater 142 and the lower sheet heater 140 of thesheet heating unit 90 are energized. The hot liquid medium, such aswater or specialty oil for applying heat, starts flowing through theliquid passageways 145 and 149 in the mask plates 98 and 99. The onesheet holder 87 is heated to the temperature 10-50° C. lower than thesoftening point of the sheet 88.

The index table 86 is stopped, to locate the one of the one sheet holder87 in the sheet supply unit 89 as illustrated in FIG. 13. The connectorplate 122 of the upper mask plate 98 and the connector plate 120 of theretaining plate 111 are inserted respectively in the two-bracketedconnectors 128 and 129 of the solenoids 124 and 125. After insertion ofthe connector plate 122 and the connector plate 120 into thetwo-bracketed connectors 128 and 129, the solenoids 124 and 125 areenergized.

With the solenoids 124 and 125 energized, the plungers 126 and 127 arewithdrawn into the solenoids 124 and 125. The two-bracketed connectors128 and 129 pull the connector plate 122 and the connector plate 120vertically. The guide shafts 106 are pulled down by the retaining plate111. The lower mask plate 99 is lowered by the flange 113 against thespring 116. The upper mask plate 98 is pulled up against the spring 117,to widen the space between the mask plates 98 and 99 as illustrated inFIG. 14.

The retaining arm 133 is driven by the air cylinder or solenoid andinserted between the mask plates 98 and 99, while retaining the sheet 88in the air suction after the cutting from the continuous sheet 27. Thenthe retaining arm 133 is released from the air suction, to drop thesheet 88 to the receiving recess 100 in the lower mask plate 99. The airsuction is being effected through the nozzle 136, which is lowered intothe openings 101 in lowering of the lower mask plate 99. Even with thecurl, the sheet 88 is reliably contained in the receiving recess 100.

When the sheet 88 finishes being supplied, the retaining arm 133 isretracted from the mask plates 98 and 99. The solenoids 124 and 125 stopbeing energized. The mask plates 98 and 99 are pressed by the spring 117and the spring 116, to come to each other. The pressing ridge 102 of theupper mask plate 98 is received in the receiving recess 100 of the lowermask plate 99. The sheet 88 is squeezed between the mask plates 98 and99. The suction device 135 still effects air suction until the one sheetholder 87 is closed.

When the one sheet holder 87 is supplied with the sheet 88, the indextable 86 is rotated again intermittently, to convey the one sheet holder87 to the sheet heating unit 90. As illustrated in FIG. 15, the sheetheating unit 90 has the solenoid 138 under the sheet holders 87. Atwo-bracketed connector 138 a pulls the connector plate 120 of theretaining plate 111, to slide down the guide shafts 106. The lower maskplate 99 is pulled by the flange 113 of the guide shafts 106, andlowered against the spring 116. The upper mask plate 98 follows thedescent of the lower mask plate 99 under the bias of the spring 117. Thesheet 88 still remains retained.

The one sheet holder 87 is pulled down. The heater head 141 of the lowersheet heater 140 is inserted into the openings 101, to heat the bottomof the sheet 88. After the descent of the one sheet holder 87, the uppersheet heater 142 is lowered from the upper mask plate 98 by the aircylinder, the solenoid and the like. The heater head 143 is insertedinto the openings 103. The portions of the sheet 88 emerging through theopenings 101 and 103 are heated as hot as 150° C. With the hot liquidmedium such as water or specialty oil circulated through the liquidpassageways 145 and 149 in the mask plates 98 and 99, the portion of thesheet 88 masked in contact with the one sheet holder 87 and excludedfrom the vacuum/air-pressure forming are heated to the temperature10-50° C. lower than the softening point of the sheet 88.

Heating of the sheet 88 is finished when the temperature near to thesheet 88 comes up to the predetermined value. The upper sheet heater 142is raised first. Then the solenoid 138 finishes being energized. The onesheet holder 87 is raised by the bias of the spring 116. It is alsopossible to measure preheating time experimentally for heating the sheet88 with the heaters, and to finish preheating the sheet 88 when themeasured time lapses.

After heating the sheet 88, the index table 86 is rotated again, toconvey the one sheet holder 87 to the forming unit 91. The forming unit91 has the single solenoid under the sheet holders 87, in a mannersimilar to the sheet heating unit 90. The one sheet holder 87 is loweredagain. As illustrated in FIG. 16, the female mold 153 is under the lowermask plate 99. With the one sheet holder 87 pulled down, the female mold153 is inserted in the openings 101. After the descent of the one sheetholder 87, the male mold 154 is moved down lower than the upper maskplate 98 by the air cylinder, the solenoid and the like, and insertedinto the openings 103.

When the male mold 154 is lowered, the air suction is effected throughthe sucking passageway 155 in the female mold 153, to keep the sheet 88in tight contact with the female mold 153 after the heating andsoftening. The air pressurization is effected through the male mold 154to press the sheet 88 against the female mold 153. Then the disk-likeportions 20 are formed in the sheet 88 with high precision. No wrinklesoccur, as the portion of the sheet 88 in the one sheet holder 87 hasbeen heated.

After the forming of the disk-like portions 20, the male mold 154 israised, before the one sheet holder 87 is raised. The index table 86 isrotted again. As illustrated in FIG. 12, the one sheet holder 87 isconveyed to the lower, where the sheet 88 is cooled in advance of nextunit for the punching. For the cooling, the sheet 88 can be left tostand as it is for a predetermined duration. Or air may be caused toblow the sheet 88 to cool the same forcibly.

After cooling of the sheet 88, the index table 86 is rotated again. Theone sheet holder 87 is conveyed to the first punching unit 93, where thebearing hole 17 a is cut in the disk-like portions 20 on the sheet 88 bythe punch and the die. The scraps created by cutting the bearing hole 17a are dropped through the die to exit to the outside.

The sheet 88 in which the bearing hole 17 a is formed is conveyed to thesecond punching unit 94 by rotation of the index table 86. In the secondpunching unit 94, the slots 23 of the arc shape is cut in the disk-likeportions 20 on the sheet 88 by the punch and the die. In the fashionsimilar to the first punching unit 93, the scraps created by cutting theslots 23 are dropped through the die to exit to the outside.

The sheet 88 worked in the second punching unit 94 is conveyed to thethird punching unit 95 by rotation of the index table 86. In the thirdpunching unit 95, the contour of the disk-like portions 20 is cut in thesheet 88. The disks 17 are dropped into the disk container whichreceives the disks 17. The disk container, when filled with a greatnumber of the disks 17, is conveyed to a line for the spool 5. In placeof the disk container as filled, a new container is positioned in thethird punching unit 95. In repetition of those steps, the disks 17 areproduced in successive fashion.

In the above embodiment, the hot liquid medium such as water orspecialty oil applies heat to the sheet holders 87. Electrically heatedwires or a feeder slip ring is also usable. Note that, if a product tobe formed by the vacuum/air-pressure forming has an undercut, it ispreferable to provide the female mold 153 with a push-out mechanism forpushing the sheet 88 up.

The number of the openings 101 and 103 for defining the heated range ofthe sheet 88 is set equal to the number of the disk-like portions 20.However it is possible that each of openings is twice as great as one ofthe disk-like portions 20, similarly to the openings 75 in FIG. 9.Further, a pair of single openings can be formed for a train of theplurality of the disk-like portions 20 to be formed at one time,similarly to the single opening 76 in FIG. 10.

In the above embodiment, the five (5) of the disks 17 are formed at onetime. Of course the present invention is applicable to forming of agreater number of the disks 17 at one time in two or three lines as amatrix form, as illustrated in FIG. 17 with a sheet holder 160 as maskdevice. It is also possible in FIG. 18 to dispose a ring-like projection161 b around a bottom of an opening 161 a in an upper mask plate 161,for contact with a sheet 162 as squeezed. The size of the opening 161 ais set considerably greater than the disks 17 in view of preventing thering-like projection 161 b from influencing the disk-like portions 20.

It is further possible in the forming unit 91 to form a positioningportion at the center of each of the disk-like portions 20 in a sizesmaller than the bearing hole 17 a. In the first punching unit 93, thebearing hole 17 a can be cut by utilizing the positioning portion. Thisraises concentricity between the disk-like portions 20 and the bearinghole 17 a. It is also possible to set up a slit punching unit instead ofthe sheet cooling unit 92. The slit punching unit can be adapted tocutting bend slits in the periphery of the disk-like portions 20. Thedisk-like portions 20 can be rendered movable from the sheet 88 inminute fashion in any direction, without removal from the sheet 88.

Still another preferred disk producing apparatus is described now. Asillustrated in FIG. 19, units for the disk production are rectilinearlyarranged in similar fashion to the first preferred embodiment. A sheetsupply unit 165 is substantially the same as the sheet supply unit 28 ofFIG. 3. A sheet winding unit 166 is substantially the same as the sheetwinding unit 33. Those are not described any further in detail.

The sheet supply unit 165 supplies a sheet heating unit 167 with acontinuous sheet 171 (See FIG. 20) of thermoplastic resin. The sheetheating unit 167, as illustrated in FIG. 20, has a mask device 170including an upper mask plate 168 and a lower mask plate 169. Thecontinuous sheet 171 is conveyed between the mask plates 168 and 169.The upper mask plate 168 has five greater openings 168 a larger than thedisks 17, and two smaller openings 168 b smaller than the greateropenings 168 a. Similarly the lower mask plate 169 has five greateropenings 169 a and two smaller openings 169 b. The smaller openings 168b and 169 b are adapted to heating the continuous sheet 171 at portionsformed to be retainable portions used in conveyance of the continuoussheet 171.

The upper mask plate 168 is secured to guide shafts 173 erected on thelower mask plate 169, and is vertically movable along the guide shafts173 by means of hydraulic cylinders, air cylinders, cams, and the like.The upper mask plate 168, when lowered, squeezes the continuous sheet171 between it and the lower mask plate 169, and prevents the continuoussheet 171 from being deformed. As is not shown, the inside of the maskplates 168 and 169 respectively has a liquid passageway, through whichhot liquid medium, such as water or specialty oil for applying heat, iscirculated, in the same manner as the former embodiments. The hot liquidmedium heats the continuous sheet 171 to the temperature 10-50° C. lowerthan a softening point of the continuous sheet 171.

As illustrated in FIG. 21, a upper sheet heater 175 and a lower sheetheater 176 are disposed so that the mask device 170 lies between them. Ablock 177 incorporates a cartridge heater 175 a. A block 178incorporates a cartridge heater 176 a. The block 177 and 178 arerespectively formed of material with high heat conductivity, such asiron or aluminum. The cartridge heaters 175 a and 176 a are controlledso that the blocks 177 and 178 surface temperature of 400±5° C., to heatthe portions of the continuous sheet 171 emerging through the greateropenings 168 a and 169 a as hot as 150° C. Heating of the continuoussheet 171 is finished when the temperature near to the continuous sheet171 as measured comes up to 150° C. as predetermined. It is alsopossible to measure preheating time experimentally for heating thecontinuous sheet 171 with the heaters, and to finish preheating thecontinuous sheet 171 and convey the continuous sheet 171 when themeasured time lapses.

There are regulating recesses 177 a and 178 a in the blocks 177 and 178in positions confronted respectively with the greater openings 168 a and169 a in the mask plates 168 and 169. If it were not for the regulatingrecesses 177 a and 178 a, it would be likely that portions of thecontinuous sheet 171 emerging through the greater openings 168 a and 169a would have unevenness in temperature: the center of each portion wouldbe hotter than the periphery. There would occur distortion in disks.However the use of the regulating recesses 177 a and 178 a isadvantageous, as their distance to the continuous sheet 171 is increasedfrom each periphery of the portions to be heated toward each center ofthe portions.

The continuous sheet 171 heated by the sheet heating unit 167 isconveyed to a forming unit 180, where the heated portions of thecontinuous sheet 171 are tightly contacted on a mold set by thevacuum/air-pressure forming the same as the former embodiments, to formthe disk-like portions 20 in FIGS. 22A and 22B with high precision. Thecontinuous sheet 171 is not melted, stuck on the sheet holders 87, ortorn in irrecoverable fashion. The portion of the continuous sheet 171other than the portions for the disk-like portions 20 is also heated bythe mask plates 168 and 169 and swellable sufficiently, so that nowrinkles occurs in the continuous sheet 171.

A positioning portion 181 and a retainable portion 182 are formed by thevacuum/air-pressure forming. The positioning portion 181 is located atthe center of the disk-like portions 20 at a radius smaller than thebearing hole 17 a. The retainable portion 182 is located in each ofpositions heated through the smaller openings 168 b and 169 b in themask plates 168 and 169. The positioning portion 181 and the retainableportion 182 have respective conical shapes inclusive of conical faces181 b and 182 b in inclination and bottom faces 181 a and 182 a. Thebottom faces 181 a and 182 a are substantially flat. The positioningportion 181 and the retainable portion 182 respectively receiveinsertion of a positioning pin and a conveying pin. In this insertion,the conical faces 181 b and 182 b operate for guiding the pins into thepositioning and retainable portions 181 and 182.

FIG. 22C illustrates construction of the forming unit 180. A female moldplate 179 is mounted on the stationary support 43, and includes five (5)disk-molding female molds 179 a aligned in the conveying direction ofthe continuous sheet 171. Five (5) positioner-molding female molds 179 bare also aligned, and respectively located at the centers of thedisk-molding female molds 179 a. Two (2) retainer-molding female molds179 c are arranged in the width direction of the continuous sheet 171. Amale mold plate 184 is mounted on the movable support 45, and includesfive (5) disk-molding male molds 184 a, five (5) positioner-molding malemolds 184 b, and two (2) retainer-molding male molds 184 c. Eachcombination of the positioner-molding female molds 179 b and thepositioner-molding male molds 184 b forms the positioning portion 181.Each combination of the retainer-molding female molds 179 c and theretainer-molding male molds 184 c forms the retainable portion 182.

The continuous sheet 171 is conveyed by a sheet conveyor 183 utilizingthe retainable portion 182. In the sheet conveyor 183, a receivingrecess 185 a is formed in a top of a sheet clamp 185. As illustrated inFIG. 23, the retainable portion 182 is inserted into the receivingrecess 185 a in the course of conveying the continuous sheet 171. Thereceiving recess 185 a is open in a direction in reverse to conveyanceof the continuous sheet 171, of which conveyance inevitably causes thereceiving recess 185 a to receive the retainable portion 182.

The sheet clamp 185 is mounted on a guide shaft 186 disposed in parallelwith a conveying path of the continuous sheet 171. Slide bearings (notshown) render the sheet clamp 185 slidable along the guide shaft 186.The sheet clamp 185 is connected to a belt 188, which is disposed on theperiphery of pulleys 187 a and 187 b under the guide shaft 186. When thepulley 187 a is rotated by a motor 189, the sheet clamp 185 is slid bythe guide shaft 186.

Above the sheet clamp 185 is located a conveying pin 190, which can beslid by driving a solenoid 191, between an upwards retracted positionand a downwards protruded position. When protruded downwards, theconveying pin 190 is inserted in the retainable portion 182 at thereceiving recess 185 a. An inclined face 190 a of the conveying pin 190is contacted on the conical face 182 b of the retainable portion 182, toposition the retainable portion 182, which is clamped between theconveying pin 190 and the receiving recess 185 a at the same time. Theconveying pin 190, while the retainable portion 182 is clamped, is movedto a position indicated by the phantom line, to convey the continuoussheet 171 in intermittent fashion.

In a position downstream from the sheet clamp 185, a sheet retainingmechanism 192 is disposed for pressing the continuous sheet 171. Thesheet retaining mechanism 192 includes a pressing pin 194 and a table195. The pressing pin 194 is movable with a solenoid 193. The table 195is located under the continuous sheet 171. After conveyance of thecontinuous sheet 171, the pressing pin 194 is protruded by the solenoid193, to squeeze the continuous sheet 171 between it and the table 195 tokeep the continuous sheet 171 immovable after the stop. A rubber head194 a is fixed on the bottom of the pressing pin 194, to retain thecontinuous sheet 171 reliably and avoid scratching the continuous sheet171.

A dancer roller 196 is disposed past the sheet retaining mechanism 192,for absorbing looseness of the continuous sheet 171 while applyingsufficient tension thereto. Note that the conveying pin 190 and thepressing pin 194 may be protruded by use of air cylinders, cams or thelike, instead of the solenoids 191 and 193.

After the forming unit 180 forms the disk-like portions 20, thepositioning portion 181 and the retainable portion 182, the continuoussheet 171 is conveyed to a slit punching unit 198. In the slit punchingunit 198, a punch and a die, known in the art, form two kinds of bendslits 199 a and 199 b in arcuate shapes in the periphery of thedisk-like portions 20 as illustrated in FIGS. 24A and 24B. The disk-likeportions 20 remain connected to the continuous sheet 171 via bridgeportions 199 c defined by the bend slits 199 a and 199 b. The disk-likeportions 20 are rendered movable from the continuous sheet 171 in minutefashion in any direction, without removal from the continuous sheet 171.Scraps created by cutting the bend slits 199 a and 199 b are droppedthrough the die to exit to the outside.

After the slit punching, the continuous sheet 171 is conveyed by thesheet conveyor 183 to a first punching unit 200. As illustrated in FIG.25A, the first punching unit 200 has a punch/die set 201 for cutting thebearing hole 17 a and the slots 23 in the disk-like portions 20 at thesame time. The punch/die set 201 includes a punch 202 above thecontinuous sheet 171 and a die 203 under the continuous sheet 171. Thecenter of the punch 202 has a positioning pin 204, to be inserted in thepositioning portion 181 to position the disk-like portions 20.

A bottom of the positioning pin 204 is protruded downwards further thanthe punch 202. As illustrated in FIG. 25B, the positioning pin 204 isfirst received in the positioning portion 181 when the punch 202 islowered, to position the disk-like portions 20. Afterwards the bearinghole 17 a and the slots 23 are cut. The bottom of the positioning pin204 is provided with a conical face 204 a in inclination associated withthe conical face 181 b of the positioning portion 181. The contact ofthe conical face 204 a with the conical face 181 b reliably guides thepositioning portion 181. With the minute mobility of the disk-likeportions 20 having the bend slits 199 a and 199 b, concentricity intreating the disk-like portions 20 between the vacuum/air-pressureforming and the punching is kept adequate. Scraps 205 formed by cuttingthe bearing hole 17 a and the slots 23 are dropped through the die 203to exit to the outside.

The continuous sheet 171 having the bearing hole 17 a and the slots 23is conveyed to a second punching unit 206. As illustrated in FIG. 26A,the second punching unit 206 has a punch/die set 207 for punching thecontour of the disk-like portions 20 to cut out the disks 17. Thepunch/die set 207 includes a punch 208 above the continuous sheet 171and a die 209 under the continuous sheet 171. The center of the punch208 has a positioning pin 210, to be inserted in the bearing hole 17 ato position the disk-like portions 20.

A bottom of the positioning pin 210 is protruded downwards further thanthe punch 208. As illustrated in FIG. 26B, the positioning pin 210 isfirst received in the bearing hole 17 a when the punch 208 is lowered,to position the disk-like portions 20. Afterwards the disk contour ispunched. When the positioning pin 210 is inserted in the bearing hole 17a, the disk-like portions 20 are minutely moved by the virtue of thebend slits 199 a and 199 b, so that concentricity in treating thedisk-like portions 20 between the vacuum/air-pressure forming and thepunching is kept ade quate.

The disks 17 are dropped under the die 209, and collected in a diskcontainer. Note that the second punching unit 206 can be provided with apush back device, so that the disks 17 after being punched away can bereturned to the continuous sheet 171 after the punching. For thisstructure, a disk withdrawing unit can be added downstream from thesecond punching unit 206 for withdrawing the disks 17 from thecontinuous sheet 171.

Referring to FIG. 19, in operation, an operating command is entered intothe disk producing apparatus, which starts conveyance of the continuoussheet 171 from the sheet supply unit 165 to the sheet heating unit 167.In the sheet heating unit 167 as illustrated in FIGS. 20 and 21, theupper mask plate 168 of the mask device 170 is driven by the hydrauliccylinders, the air cylinders, the cams, and the like, is lowered alongthe guide shafts 173. The continuous sheet 171 is squeezed between themask plates 168 and 169, and retained.

The portions of the continuous sheet 171 emerging through the greateropenings 168 a and 169 a and the smaller openings 168 b and 169 b areheated by the sheet heaters 175 and 176 having the surface temperatureof nearly 400° C. In the blocks 177 and 178, the distance from theregulating recesses 177 a and 178 a to the continuous sheet 171 isincreased from each periphery of the portions to be heated toward eachcenter of the portions. The center of each portion does not become anyhotter than the periphery. With the sheet temperature regulated evenly,no distortion occurs in the disks. The continuous sheet 171 is heated ashot as 150° C. The mask plates 168 and 169 are being heated by the hotliquid medium, such as water or specialty oil, so that the maskedportion of the continuous sheet 171 is heated to the temperature 10-50°C. lower than the softening point of the continuous sheet 171.

The continuous sheet 171 heated in the sheet heating unit 167 isconveyed to the forming unit 180, where heated portions of thecontinuous sheet 171 are contacted on a mold by the vacuum and/or theair-pressure, and forms the disk-like portions 20, the positioningportion 181 and the retainable portion 182 with high precision asillustrated in FIGS. 22A and 22B. The portions of the continuous sheet171 required for the forming have been heated to the softening point.The other portion is heated 10-50° C. lower than the softening point, sothat no wrinkles or breakage occurs in the continuous sheet 171.

In FIG. 23, the retainable portion 182 is inserted into the receivingrecess 185 a while the continuous sheet 171 is conveyed. The solenoid191 causes the conveying pin 190 to extend downwards, and to enter theretainable portion 182. The inclined face 190 a of the conveying pin 190is contacted on the conical face 182 b of the retainable portion 182, toposition the retainable portion 182. The conveying pin 190 and thereceiving recess 185 a clamps the retainable portion 182.

When the retainable portion 182 is retained on the sheet clamp 185, themotor 189 is driven, to rotate the pulley 187 a in the clockwisedirection. The sheet clamp 185 is moved along the guide shaft 186 to theright as viewed in the drawing, with the continuous sheet 171 retainedon the retainable portion 182. Once the sheet clamp 185 comes to theposition indicated by the phantom lines, the sheet clamp 185 is stopped.The pressing pin 194 of the sheet retaining mechanism 192 is protrudedby the solenoid 193 downwards, and squeezes the continuous sheet 171between the rubber head 194 a and the table 195, to hold the continuoussheet 171 as stopped.

The continuous sheet 171 provided with the disk-like portions 20, thepositioning portion 181 and the retainable portion 182 is conveyed fromthe forming unit 180 to the slit punching unit 198, where the punch andthe die form the bend slits 199 a and 199 b for the disk-like portions20 as illustrated in FIGS. 24A and 24B. The scraps from the bend slits199 a and 199 b are dropped through the die to exit.

The continuous sheet 171 after the slit punching is conveyed to thefirst punching unit 200 by the sheet conveyor 183. In the first punchingunit 200, as illustrated in FIGS. 25A and 25B, the punch 202 is loweredby the hydraulic cylinders, the air cylinders, the cams, and the like.The positioning pin 204 is first inserted in the positioning portion181. The contact of the conical face 204 a with the conical face 181 bguides the positioning portion 181. The disk-like portions 20 arepositioned in well-centered fashion adjusted through the bridge portions199 c.

The punch 202 is further lowered, and cooperates with the die 203 to cutthe bearing hole 17 a and the slots 23 in the disk-like portions 20. Thepositioning of the positioning portion 181 with the positioning pin 204is effective in raising concentricity between the forming of thering-like lip 17 b and the cutting of the bearing hole 17 a and theslots 23. The scraps 205 created from the bearing hole 17 a and theslots 23 are dropped through the die to exit.

The continuous sheet 171 in which the bearing hole 17 a and the slots 23are formed is conveyed to the second punching unit 206, where the punch208 is lowered by the hydraulic cylinders, the air cylinders, the cams,and the like, as illustrated in FIGS. 26A and 26B. The positioning pin210 is first inserted in the bearing hole 17 a. The disk-like portions20 are positioned in well-centered fashion adjusted through the bridgeportions 199 c.

The punch 208 is further lowered, and cooperates with the die 209 to cutthe contour of the disk-like portions 20 to punch out the disks 17. Thepositioning of the bearing hole 17 a with the positioning pin 210 iseffective in raising concentricity between the disk contour and thebearing hole 17 a. The disks 17 are dropped under the die 209, collectedin the disk container, and conveyed to a line for assemblage of thespool 5.

In the above, the retainable portion and the positioning portion haverespective recesses in which the pins are inserted for the retention andpositioning. It is instead possible that a retainable portion and apositioning portion have respective projections, which may be retainedand positioned by being inserted in respective recesses formed in aretaining device and a positioning device. Furthermore, it is possiblenot to form any additional positioning portion, but to use the ring-likelip of the disk-like portion as positioning portion, to be fitted on apositioning device shaped in association therewith.

In any of the above embodiments, only the disks 17 are produced. Thedisks 16 are produced separately from the disks 17. However the presentinvention is applicable for a disk producing apparatus in which thedisks 16 and 17 are produced from the same continuous sheet at the sametime.

The embodiment is described as a variant of the foregoing embodiment. InFIG. 27, a continuous sheet 215 has a great width, and subjected to thevacuum/air-pressure forming to form 10 of the disk-like portions 20 in2×5 matrix. The arrow indicates a direction of conveyance. To preheatthe continuous sheet 215 before the forming, a mask plate having 10openings is used. Positioning portions 216 and retaining portions 217are formed at the same time as the disk-like portions 20. In a slitpunching unit, as illustrated in FIG. 28, bend slits 218 and 219 inarcuate shapes are formed around the disk-like portions 20. All of thedisk-like portions 20 have a common shape.

In FIG. 29, the disk-like portions 20 are arranged in first and secondlines. In the first punching unit, the bearing hole 17 a and the slots23 are cut in disk-like portions of the first line of the disk-likeportions 20. The bearing hole 16 a is cut in disk-like portions of thesecond line. In the second punching unit, the contour of all thedisk-like portions 20 is cut, so that the disks 16 and 17 are produced.Note that, if the disks 16 and 17 as cut out are mixed up, they must besubsequently separated prior to the assembly of the spool 5. It ispreferred that there are two separate exit stations respectivelyassociated with the disks 16 and 17 as receptacles of the die.

In the above, the single sheet heater is used for heating the pluralportions to be the disk-like portions. However it is likely that thereis unevenness in temperature between positions on the sheet heater. FIG.30 illustrates an embodiment to solve this problem: plural sheet heaters221 are disposed in positions associated with respective openings 220 ina mask plate, and individually controlled in temperature. This iseffective in regularizing quality of disks.

In the above embodiments, each sheet heater includes the metal block andthe cartridge heater incorporated in it. Instead, near infrared rayheaters, such as halogen lamp heaters, may be used.

Each set of a punch and a die used in the slit punching unit, the firstpunching unit and the second punching unit means at a faster rate thegreater the number of the portions punched at the same time, and iscostly when replaced by a new set. The present invention is applicablein a disk producing apparatus in which six disk-like portions are formedat one time, and then two or three of the disk-like portions are punchedat one time. This can reduce the speed of the means of the sets of apunch and a die, and thus reduce the expenses for disk production.

In any of the above embodiments, the sheet is heated sufficiently at onetime. Alternatively the sheet can be heated at a plurality of timessuccessively, in view of evenness and high performance in the heating.

In the mold, the air passageway for air suction is formed. It ispossible to eliminate the air passageway, and to form the mold frommetal or ceramics having air permeability, so as to suck a sheet inregular fashion to regularizing quality of disks.

To inspect disks as produced, the disks must be aligned in conventionaltechniques. However the apparatus of the present invention makes itpossible to inspect the disks before punching of their contour: afterthe punching of the hole and the openings, the disk-like portions can beinspected by means of image recognition as to their contour shape andopened positions. This makes it unnecessary to align the disk asproduced, and can raise efficiency in production.

Although the present invention has been fully described by way of thepreferred embodiments thereof with reference to the accompanyingdrawings, various changes and modifications will be apparent to thosehaving skill in this field. Therefore, unless otherwise these changesand modifications depart from the scope of the present invention, theyshould be construed as included therein.

What is claimed is:
 1. A disk producing apparatus for a photo filmcassette including a spool core on which photo film is wound in a formof a roll, a cassette shell for containing said spool core in rotatablefashion, and a pair of disks in each of which a bearing hole is formed,and each of which is respectively secured to first and second ends ofsaid spool core, for regulating edges of said photo film, said diskproducing apparatus comprising: a sheet supply unit for supplying asheet of thermoplastic synthetic resin; a mask device for partiallymasking said sheet, and at least one opening formed through said maskdevice; a sheet heating unit for heating a portion of said sheet exposedthrough said mask device at a temperature higher than a softening pointof said sheet, said sheet heating unit including a first heating memberand a regulating recess formed in said first heating member, saidregulating recess of said first heating member is confronted with saidopening in said mask device, and is retracted most deeply at a positioncorresponding to a center of said opening; a forming unit for subjectingsaid portion of said sheet exposed through of said mask to one of vacuumforming, air-pressure forming, and vacuum/air-pressure forming, so as toform a disk-shaped portion in said sheet; wherein said sheet heatingunit is operative to be moved from a first position which is outsidesaid forming unit to a second position which is inside said formingunit; a punching unit for cutting said bearing hole and a contour ofsaid disks in said disk-shaped portion, to produce said disks; and adisk withdrawing unit for withdrawing said disks from said sheet.
 2. Adisk producing apparatus as defined in claim 1, wherein said forming andsaid punching units are operative to form ring-shaped lips on respectiveperipheries of said disks, projected toward said roll of said photofilm, contacted on said edges of said roll, for preventing said rollfrom being loosened.
 3. A disk producing apparatus as defined in claim2, wherein said at least one opening formed through said mask device hasa size which is greater than said disks, and said portion of said sheetexposed through said mask device is operative to be heated by said sheetheating unit.
 4. A disk producing apparatus as defined in claim 3,further comprising a mask heating device for heating said mask device attemperature lower than said softening point of said sheet while saidmask device masks said sheet partially.
 5. A disk producing apparatus asdefined in claim 4, wherein said mask heating device is operative toprovide heat to said mask at a temperature 10-50° C. lower than saidsoftening point of said sheet.
 6. A disk producing apparatus as definedin claim 4, wherein said mask device includes first and second platesbetween which said sheet is squeezed, to avoid deforming said sheet. 7.A disk producing apparatus as defined in claim 6, wherein said at leastone opening formed through said mask device is formed from: at least onefirst opening formed through said first plate, said at least one firstopening has a size greater than said disks, said portion of said sheetexposed through said mask device is operative to be heated by said sheetheating unit while said sheet is supported on said first plate; and atleast one second opening formed through said second plate andsubstantially confronted with said first opening, said portion of saidsheet exposed through said mask device is operative to be heated by saidsheet heating unit while said sheet is supported on said second plate.8. A disk producing apparatus as defined in claim 7, further comprisinga ring-shaped projection formed on an edge of said first opening,projected toward said second plate, and received in said second openingwhen said first and second plates are contacted on each other, forpositioning said sheet between said first and second plates incooperation with said second opening.
 9. A disk producing apparatus asdefined in claim 6, wherein said sheet heating unit further includes: asecond heating member opposed to said first heating member, and aregulating recess formed in said second heating member, said regulatingrecess of said second heating member is confronted with said opening insaid mask device, and is retracted most deeply at a positioncorresponding to a center of said opening, wherein said regulatingrecess formed in said first heating member and said regulating recessformed in said second heating member are retracted most deeply at aposition corresponding to a center of said opening for rendering atemperature of said sheet at said center substantially as high as atemperature of said sheet at a periphery of said opening.
 10. A diskproducing apparatus as defined in claim 4, wherein said at least oneopening is single, and has a length substantially equal to a cumulativevalue of diameters of said disks.
 11. A disk producing apparatus asdefined in claim 4, wherein said at least one opening comprises aplurality which are arranged in a line.
 12. A disk producing apparatusas defined in claim 11, wherein said plurality of said openingrespectively have a length substantially twice as great as a diameter ofsaid disks, and arranged in a longitudinal direction thereof.
 13. A diskproducing apparatus as defined in claim 11, wherein said sheet heatingunit includes a plurality of sheet heating devices confrontedrespectively with said plurality of said openings.
 14. A disk producingapparatus as defined in claim 4, wherein said sheet supply unit isoperative to supply a continuous sheet which is conveyed in asubstantially rectilinear fashion from said sheet supply unit, throughsaid sheet heating unit, through said forming unit and toward saidpunching unit.
 15. A disk producing apparatus as defined in claim 14,wherein said forming unit forms simultaneously N disk-shaped portionsarranged in a direction of conveying said sheet, where N≧2; and saidpunching unit produces simultaneously N disks from said N disk-shapedportions.
 16. A disk producing apparatus as defined in claim 14, whereinsaid forming unit forms simultaneously N disk-shaped portions arrangedin a width direction of said sheet, where N≧2; and said punching unitproduces simultaneously N disks from said N disk-shaped portions.
 17. Adisk producing apparatus as defined in claim 14, further comprising: aretainer-forming device, disposed in said forming unit, for forming aretainable portion in said sheet and near to an edge thereof when saidforming unit forms said disk-shaped portion; a retaining device,disposed in a conveying path of said sheet, for retaining saidretainable portion; and a conveying device, movable in one directionwithin a predetermined range, said retaining device being mounted onsaid conveying device, said conveying device moving said retainingdevice retaining said retainable portion, so as to convey said sheetintermittently.
 18. A disk producing apparatus as defined in claim 17,further comprising: a positioner-forming device, disposed in saidforming unit, for forming a positioning portion in said sheet inassociation respectively with said disk-shaped portion when said formingunit forms said disk-shaped portion; and a positioning device, disposedin said punching unit, for positioning said sheet with said positioningportion, in cutting said bearing hole and said contour of said disks.19. A disk producing apparatus as defined in claim 18, wherein saidretainable portion has a recess or a projection, and said positioningportion has a recess or a projection.
 20. A disk producing apparatus asdefined in claim 4, further comprising a slit cutting unit, disposedbetween said forming unit and said punching unit, for cutting at leastone first bend slit in an outside of said disk-shaped portion to extendalong part of a periphery thereof, said first bend slit rendering aposition of said disk-shaped portion adjustable minutely relative tosaid sheet.
 21. A disk producing apparatus as defined in claim 20,wherein said slit cutting unit further cuts a second bend slit in saidsheet, said second bend slit being disposed near to an outside of saidfirst bend slit, and said first and second bend slits surrounding saiddisk-shaped portion, for rendering flexible a portion of said sheetbetween said first and second bend slits.
 22. A disk producing apparatusas defined in claim 21, wherein said slit cutting unit is operative toform said first bend slit to have a range over a half of said peripheryof said disk-shaped portion, and said second bend slit to have a rangeunder a half of said periphery of said disk-shaped portion.
 23. A diskproducing apparatus as defined in claim 4, wherein said forming unitforms first and second lines of disk-shaped portions, said first line isused for forming a first one of said disks, said second line is used forforming a second one of said disks, said first one has a firstopening-cutting pattern, said second one has a second opening-cuttingpattern different from said first opening-cutting pattern.
 24. A diskproducing apparatus as defined in claim 23, wherein said punching unitinitially cuts said first opening-cutting pattern in said first line ofsaid disk-shaped portions, and cuts said second opening-cutting patternin said second line of said disk-shaped portions; and subsequently saidpunching unit cuts said contour of said first and second ones of saiddisks in said first and second lines of said disk-shaped portions.
 25. Adisk producing apparatus as defined in claim 24, further comprising aslit cutting unit, disposed between said forming unit and said punchingunit, for cutting at least one first bend slit in an outside of saiddisk-shaped portion to extend along part of a periphery thereof, saidfirst bend slit rendering a position of said disk-shaped portionadjustable minutely relative to said sheet.
 26. A disk producingapparatus as defined in claim 4, wherein said sheet has a predeterminedsize; said sheet supply unit, said sheet heating unit, said forming unitand said punching unit are arranged along one arc; and furthercomprising an index table, disposed at a center of arrangement of saidsheet supply unit, said sheet heating unit, said forming unit and saidpunching unit, said sheet being mounted on said index table, said indextable being rotated intermittently, for passing said sheet through saidsheet supply unit, said sheet heating unit, said forming unit and saidpunching unit.
 27. A disk producing apparatus as defined in claim 26,wherein said mask device includes plural sheet holders, secured to saidindex table, arranged radially, for supporting said sheet and formasking said sheet partially; said sheet supply unit supplying saidsheet holders with said sheet; further comprising: a sheet cooling unit,arranged on a periphery of said index table and past said forming unit,for cooling said sheet after said forming unit; and a sheet exit unit,arranged on a periphery of said index table and past said punching unit,for exiting said sheet after cutting away said disks.
 28. A diskproducing apparatus as defined in claim 27, wherein said forming unitforms simultaneously N disk-shaped portions arranged in one line, whereN≧2.
 29. A disk producing apparatus as defined in claim 27, wherein saidforming unit forms simultaneously plural disk-shaped portions arrangedin a matrix.
 30. A disk producing apparatus for a photo film cassetteincluding: a spool core on which photo film is wound in a form of aroll, a cassette shell for containing said spool core in rotatablefashion, a pair of disks in each of which a bearing hole is formed, andeach of which is respectively secured to first and second ends of saidspool core, for regulating edges of said photo film; and ring-shapedlips formed respectively on a periphery of said disks integrallytherewith, projected toward said roll of said photo film, contacted onsaid edges of said roll, for preventing said roll from being loosened,said disk producing apparatus comprising: an index table rotatableintermittently; a sheet supply unit arranged on a periphery of saidindex table, for supplying a sheet of thermoplastic synthetic resin of apredetermined size; plural sheet holders, secured to said index table,arranged radially in rotatable fashion through a rotational orbit, forsupporting said sheet supplied by said sheet supply unit and for maskingsaid sheet partially, said sheet holders respectively having an uppermask with an opening and a lower mask with an opening, for respectivelyexposing a portion of said sheet; a sheet heating unit, arranged in saidrotational orbit of said sheet holders and past said sheet supply unit,said sheet heating unit having an upper heater head and a lower heaterhead for heating a portion of said sheet exposed through said sheetholders at a temperature higher than a softening point of said sheet, atleast one of said upper heater head and said lower heater is operativeto be respectively inserted into one of said upper mask opening and saidlower mask opening; a forming unit, arranged in said rotational orbit ofsaid sheet holders and past said sheet heating unit, for subjecting saidexposed portion to one of vacuum forming, air-pressure forming, andvacuum/air-pressure forming, so as to form a disk-shaped portion in saidsheet; a sheet cooling unit, arranged in said rotational orbit of saidsheet holders and past said forming unit, for cooling said sheet aftersaid forming unit; a punching unit, arranged in said rotational orbit ofsaid sheet holders and past said sheet cooling unit, for cutting saidbearing hole and a contour of said disks in said disk-shaped portion, toproduce said disks; and a sheet exit unit, arranged in said rotationalorbit of said sheet holders and past said punching unit, for exitingsaid sheet after cutting away said disks.